Bulk waveguide resonators for the ultraviolet part of the spectrum

The output power of ultraviolet electron-pumped ZnO lasers was increased by employing waveguide resonators of transverse size (waveguide thickness) greater than the depth of the active layer. The output power of multielement resonators of this type cooled to 80 K reached 100 kW for an efficiency close to 15%. The size of the samples was 2×0.3×8 mm and the pump pulse duration was 10^–7 sec. Single crystals of ZnO were prepared by the hydrothermal method.